Active Shift Transmission, Transmission Control Unit and Automobile

ABSTRACT

The object of the invention is to provide a less expensive active transmission control system for an automobile, capable of disconnecting an engine, without increasing the number of dog clutches. In an active shift transmission, a second intermediate shaft is provided between a transmission input shaft connected with an engine and a transmission output shaft, and the transmission ratio is determined by the product of gear ratios of two sets of transmission gears. Further, a differential gear box is connected between both intermediate shafts and a motor is connected to the third shat of this differential gear box, so that the engine torque is borne by the motor on a temporary basis, whereby active transmission is performed. When the transmission gear of the input shaft is released, the engine rotation loss at the time of regenerative braking can be eliminated by disconnecting the engine.

RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.10/920,248, filed Aug. 18, 2004, issued as U.S. Pat. No. 7,226,379,which claims priority to Japanese application serial no. 2003-312078,filed on Sep. 4, 2003, the content of which is hereby incorporated byreference into this application.

FIELD OF THE INVENTION

The present invention relates to the control of a transmission, inparticular, to the art of reducing a transmission shock by cooperatingcontrol of an engine, motor and transmission.

BACKGROUND OF THE INVENTION

In the prior art automobile transmission, a planetary gear or countershaft type transmission mechanism has been utilized. It is a commonpractice to change the speed by engaging the separately installed clutchwith the gear steps having different transmission ratios on a selectivebasis. This is a method for shifting the engine torque from the frontposition gear to the next position gear by changing the engagement ofthe friction clutch. Since friction loss occurs at the time of gearshift and the clutch is a passive device, torque transfer cannot beachieved in principle at the time of downshifting. This has been aproblem in the prior art.

To solve this problem, the applicants of the present invention filed anapplication for an active transmission method for regenerating theenergy discharged at the time of up-shifting, using a motor as an activedevice, and for pumping up the torque from the high-shift position oflower power to the low-shift position of higher power at the time ofdown-shifting as indicated by Japanese Patent Laid-Open No. 2002-204504.

Although the aforementioned active transmission system is capable ofsolving the problems of the transmission using a prior art clutch, itrequires a large-capacity motor for gear shift. The required motorcapacity is calculated by (transmission torque by motor speed). Themaximum transmission torque is equal to the maximum engine torque. In acommon transmission, the maximum motor speed is equal to the differencespeed at the time of 1-2 shift; therefore, the motor capacity of 20 kWor more is required, for example, when a 1.5 L engine is used.

To permit gear shift with the smallest possible motor, the presentapplicant filed an application for a method for ensuring a 50-percentreduction of motor capacity by using an intermediate gear as indicatedby Japanese Patent Laid-Open No. 2003-113934. Since this method does notrequire use of a clutch in the input shaft, it reduces both weight andcost.

SUMMARY OF THE INVENTION

In the aforementioned intermediate position method, the input shaft doesnot use a clutch, and therefore the engine is always connected to thetransmission. This method involves a problem in that, when aregenerative braking function as a hybrid function is used, the enginebrake is applied at all times. It goes without saying that this problemcan be solved by arranging a clutch, but this does not bring about areduction in the weight and cost.

The object of the present invention is to solve the aforementionedproblem and to provide a less costly active transmission control systemfor automobile use, while making an extensive use of the hybridfunction.

The present invention provides a gear train configuration thatdisconnects an engine from the transmission without using a clutch. Toput it more specifically, part of the gears is shifted to the side ofthe engine shaft side through modification of the layout of a gear withdog clutch, whereby engine disconnection is enabled, without allowingthe number of the dog clutches to exceed that of the intermediateposition type active shaft transmission system.

The present invention allows the engine to be disconnected from thetransmission without increasing the number of the dog clutch, therebyincreasing increase the efficiency in regenerative braking and ensuringeconomical disadvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram of an automobile with transmissionmounted thereon, as an embodiment of the present invention;

FIG. 2 is a structural diagram representing a transmission as a firstembodiment of the present invention;

FIG. 3 is an explanatory diagram of gear combinations representing achange in the torque transfer path when sequential transmission isperformed with power turned on, in the transmission shown in FIG. 2;

FIG. 4 is a list showing the gear combinations and transmission ratiowhen sequential transmission is performed, in the transmission shown inFIG. 2;

FIG. 5 is a list showing examples of the gear radius, gear ratioobtained and center distance in the transmission shown in FIG. 2;

FIG. 6 is a list showing the secondary gear combinations andtransmission ratios except for the sequential transmission in FIG. 4 inthe transmission shown in FIG. 2;

FIG. 7 is a list showing all combinations and transmission ratios in thetransmission shown in FIG. 2;

FIG. 8 is an explanatory diagram representing changes of the torquetransfer path when 2-step jump-over gear shift is performed in thetransmission shown in FIG. 2;

FIG. 9 is an explanatory diagram representing changes of the torquetransfer path when 3-step jump-over gear shift is performed in thetransmission shown in FIG. 2;

FIG. 10 is an explanatory diagram of gear combinations representingchanges of the torque transfer path at the time of power-on upshiftperformed after jump-over downshift in the transmission shown in FIG. 2;

FIG. 11 is a flowchart representing software configuration at the timeof 1-2 upshift in the transmission shown in FIG. 2;

FIG. 12 is a time chart representing a time chart showing the changes inthe torque and speed in 1-2 power-on upshift in the transmission shownin FIG. 2, and an explanatory diagram showing the torque transfer pathand dog clutch operation;

FIG. 13 is a block diagram showing the configuration of the motorcontrol used in the present invention;

FIG. 14 is a motor characteristic drawing representing the changes inmotor operating points in the motor control of FIG. 9;

FIG. 15 is a structure diagram representing the configuration of atransmission as a second embodiment of the present invention;

FIG. 16 is an explanatory drawing of gear combinations representingchanges in the torque transfer path in the case of sequentialtransmission in the power-on mode, in the transmission of FIG. 15;

FIG. 17 is a list showing the gear combinations and transmission ratiosin the case of sequential transmission in the power-on mode, in thetransmission of FIG. 15;

FIG. 18 is a list showing an example of the gear radius and obtainedgear ratio, and center distance, in the transmission of FIG. 15;

FIG. 19 is a list showing the secondary gear combinations andtransmission ratios, except for the sequential transmission of FIG. 17,in the transmission of FIG. 15; and

FIG. 20 is a list showing all the gear combinations and transmissionratios in the transmission of FIG. 15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a block diagram representing an embodiment of the presentinvention. An engine 1 as a prime mover of an automobile is connectedwith a transmission 2. An output shaft 3 drives a tire 4 through thedifferential gear. An electric motor 5 is built in the transmission 2.This motor 5 is connected with a control unit 7, and a battery 6 ismounted as a power supply of the control unit 7.

The engine 1 is provided with an electrically controlled throttle valve10, which controls the engine output in response to a request signal.

A transmission control unit 8 controls the torque and revolutionaryspeed of the motor 5 through the motor control unit 7. It also controlsthe output of the engine 1 through the engine control unit 9 andelectrically controlled throttle valve 10. Further, it providesoperation instructions to the shift actuators 25 through 28 to bedescribed later.

Here the engine control unit, transmission control unit and motorcontrol unit are shown as separate control units. It is also possible tomake such arrangements that one of these control units performs thefunction of another control unit. Further, one integrated control unitmay perform the functions of all other control units. In other words,the function of one control unit can be performed by another controlunit, that control unit need not be installed. This statement isapplicable to all embodiments shown in the present application.

FIG. 2 is a block diagram of a transmission 2 representing the firstembodiment of the present invention. The output of the engine 1 isconnected with a transmission input shaft 36. The transmission inputshaft 36 is fixed with input gears 37 and 38. A first intermediate shaft39 is arranged opposite to the input shaft 36, and transmission gears40, 41, 42, 43, 44 and 45 are mounted rotatably on the firstintermediate shaft 39. These transmission gears are equipped with dogclutches 46, 47 and 48 so that any one of the transmission gears can beengaged with the first intermediate shaft 39.

The transmission gears 40 and 41 of the first intermediate shaft 39 aremeshed with the input gears 37 and 38, and the transmission gears 42,43, 44 and 45 are meshed with driven gears 49, 50, 51 and 52.

A second intermediate shaft 53 is provided opposite to the input shaft36, and the second intermediate shaft 53 is rotatably equipped withtransmission gears 54, 55, 56, 57, 58 and 59. These transmission gearsare provided with clutches 60, 61 and 62 so that any one of thetransmission gears can be engaged with the second intermediate shaft 53.

The transmission gears 54 and 55 of the second intermediate shaft 53 arealso meshed with the input gears 37 and 38. Further, transmission gears56, 57, 58 and 59 are meshed with the driven gears 49, 50, 51 and 52fixed to the output shaft 3, respectively.

The dog clutches 46, 47, 48, 60, 61 and 62 slide to be meshed with theintended gears by means of shift forks, which are driven by shiftactuators 63, 64, 65, 66, 67 and 68.

The present embodiment is characterized in that a differential gear box31 using a planetary gear is connected to the first intermediate shaft39 and second intermediate shaft 53, and a motor 5 is connected to thethird shaft of the differential gear box 31. The revolutionary speed ofthe motor 5 is equal to the revolutionary speed of the difference of twointermediate shafts. The torque generated by the motor 5 acts in such amanner as to twist the two intermediate shafts in the directionsopposite to each other. This is equivalent to the case where the rotorand stator of the motor 5 are connected to the respective input shafts,as shown in the equivalent construction drawing. The followingdescription will be based on this equivalent construction drawing.

FIG. 3 shows an example of the operation mode of the presenttransmission. The transmission ratio of this transmission is determinedby a combination of two transmission gears. The engine torque istransferred from the input shaft 36 to either the first intermediateshaft 39 or second intermediate shaft 53. A drive mode is defined as themode where the engine torque is transferred from the intermediate shaftdirectly to the output shaft 3, while an assist mode is defined as themode where the engine torque is transferred to the output shaft 3 afterhaving been transferred to another intermediate shaft through the motor.The 1st, 2nd, 3rd, 4th and 5th gears are in the drive mode, while 0.5th,1.5th, 2.5th, 3.5th and 4.5th gears are in the assist mode.

In either mode, engine torque is transmitted through two dog clutches.To perform power-on shift, connection of either one of the dog clutchesmust be changed, with the remaining one left unchanged. Otherwise, thetorque will be suspended, and transmission feeling will be impaired.Further, means must be provided to ensure that the transmission ratio inthe assist mode will be the median value of the transmission ratio inthe drive mode. The gear ratio of each transmission gear is set bygiving consideration to these two restrictions.

FIG. 4 shows an example of the transmission ratio gained by the settinggear ratio and its combination thereof. It meets the aforementioned tworestrictions and corresponds to FIG. 3. The definition of each gearratio is given in the figure attached to FIG. 4. The transmission ratioin the assist mode is slightly smaller than the median value of thetransmission ratio in the drive mode. This is because the planned valueis intentionally misaligned, giving consideration to the motor inverterefficiency. After having aligned the following center distances, themisalignment was at most 2% or so, although it was further increasedfrom the planned value.

FIG. 5 shows the radius r1 through r18 of transmission gears forrealizing these gear ratios, and the center distances L1 through L4determined thereby. The radius and center distance are defined in thefigure attached to FIG. 4. As described above, the center distance L1 isequal with respect to transmission gears 40 and 41, and the centerdistance L4 is equal with respect to transmission gears 54 and 55;therefore, transmission gears 40 and 41 and transmission gears 54 and 55can be made to mesh each other from both sides of the input gears 37 and38. Similarly, the center distance L2 is equal with respect to thetransmission gears 42 through 45, and the center distance L3 is equalwith respect to the transmission gears 56 through 58; therefore, thesegears can be made to mesh with each other from both sides of the drivengears 49 through 52. The transmission gear 59 is used for backing up,and an idler is inserted, so there is no need of giving consideration tothe center distance L3.

Further, the input shaft 36, first intermediate shaft 39, secondintermediate shaft 53 and output shaft 3 are not arranged on a flatplane, so there is no need of meeting L1=L2, and L3=L4.

Incidentally, the transmission in FIG. 2 permits a variety ofcombinations in addition of the combination given in FIG. 3 (FIG. 4).FIG. 6 shows the combinations other than those given above. A variety ofintermediate transmission ratios can be obtained. They are transmissionratios for the engine, and this transmission also changes transmissionratio for the motor. FIG. 7 shows all combinations including thetransmission ratio for the motor. The portion enclosed by bold framesindicates transmission ratio with respect to the motor. The other showsthe gear ratio with respect to the engine. The crosshatched sectionshows the mode where the engine torque is transferred through the motor.The bold characters show the combinations of FIG. 3 (FIG. 4).Combinations of the G11 and G12, and G41 and G42 are also possible.Transmission ratio between the engine and motor is shown. This ispossible when only one gear on the output shaft side is connected. Whenthe combination shown by the bold frame is used, connection isprohibited. This is indicated by “−”. The combination marked with “×”refers to the case of double meshing, and revolution is disabled in thisstate. As described above, the transmission shown in FIG. 2 is capableof 48 transmissions ratios.

FIG. 8 shows changes in the combination when a 2-step jump-over gearshift is performed in the present transmission. The jump-over gear shiftis normally carried out by rapid step-on gas pedal, so downshift isshown. A completely reverse process is taken for jump-over upshift.However, there is hardly any request for upshift. Since this correspondsto what is called “lift foot upshift” where gas pedal is released, thereis no problem with torque interruption. All that is needed is jumpingover to the mode required in the line of transmission. The same mode asthat in the sequential shift of FIG. 1 can be used for 5-3 shift and 4-2shift. However, if the same mode as shown in FIG. 3 is to be used for3-1 shift, simultaneous changes of two dog clutches will occur, with theresult that torque interruption takes place. To solve this problem, gearshift is performed from 3 to 1.2 through 1.7. This method providessatisfactory gear shift without causing torque interruption.

FIG. 9 represents the changes in combinations for 3-step jump-over gearshift in the present transmission. Since the 3-step jump-over gear shiftis required for kick-down, the down shift is shown. In this case, 5-2shift is performed in the same mode as that in the sequential shift ofFIG. 3. If the same mode as that of FIG. 3 is to be used for 4-1 shift,torque interruption occurs. If gear shift is performed from 4 to 1.2through 2.4, satisfactory gear shift can be provided without causingtorque interruption.

FIG. 10 shows the upshift after jump-over gear shift. In both 2-step and3-step jump-over gear shifts, 1.2th gear is obtained by combinations ofG41 and G31. After the driving force has been increased by downshift,upshift is carried out by acceleration. In this case, 1.2 is reachedthrough 1.4 by the process shown in FIG. 10. Further, 3rd gear isreached through 2.6. After that, one can go back to the process shown inFIG. 3.

FIG. 11 is a flowchart representing an example of power-on upshift from1 to 2.

FIG. 12A is a time chart representing the changes in the torques andspeeds of various sections in this case, in the form corresponding tothe steps given in FIG. 11.

FIG. 12B again shows the changes in the torque transmission route ofupshift from 1 to 2 shown in FIG. 3 and meshing clutch.

Referring to FIGS. 11 and 12, the following describes the operations inthe upshift from 1 to 2.

In Step 1, while the car is driving with the transmission gears 40 (G11)and 42 (G21) engaged, the motor speed is controlled to change therevolutionary speed N2 of the second intermediate shaft 53, as shown inFIG. 12B.

In Step 2, evaluation is made to determine that the revolutionary speedN2 of the second intermediate shaft 53 has been synchronized with therevolutionary speed of the transmission gear 55 (G42).

In Step 3, the transmission control unit 8 actuates the shift actuator66, and moves the dog clutch 60 rightward, as shown in the drawing. Whenit has been engaged with the transmission gear 55, the motor 5 performsan idle rotation at the speed of (N1−N2). This can be expressed asfollows:N1=G21×No  (Equation 1)N2=Ne/G42=G11×G21/G42×No  (Equation 2)

When calculation is made by applying numerals in FIG. 4,(N1−N2)=−0.277×No. This is a negative value. Here the G11 denotes thegear ratio of the transmission gear 40, the G21 the gear ratio of thetransmission gear 42, the G42 the gear ratio of the transmission gear55, Ne the revolutionary speed of the engine 1, and N1 the revolutionaryspeed of the first intermediate shaft 39.

In Step 4, if motor torque is increased in the negative direction (adriving force for the output shaft, and a load for the engine), theinput torque of the transmission gear 55 (G42) will be increased, andthe input torque of the transmission gear 40 (G11) will be reduced, asshown in the timing chart of FIG. 12. This is a process of torquetransfer 1 of what is called torque phase.

In Step 5, the transmission control unit 8 determines if the torquetransfer 1 has terminated or not. It is intended to determine if theinput torque of the transmission gear 40 (G11) has been reduced to zeroor not. However, since it often happens that the input torque of thegear cannot be directly detected, the input torque of the gear can beconsidered as “0”, when the value of the motor transfer torque expressedin terms of the engine shaft has reached the value equal to the absolutevalue of the engine torque. For this purpose, it is necessary to get theengine torque Te in advance by detection or calculation. Its specificmethod is shown in the Japanese Patent Laid-Open No. Hei 05-240073 andJapanese Patent Laid-Open No. Hei 06-317242, and will not be describedhere.

In Step 6, the transmission control unit 8 operates the shift actuator63, as shown in FIG. 12B, and releases the transmission gear 40 (G11).Easy release is possible from the state of torque being zero. There isno change to the operation of the transmission. When the transmissiongear 40 (G11) has been released, the engine speed can be changed.

In Step 7, when the transmission control unit 8 issues a motor speedchange command, the engine speed is changed toward the revolutionaryspeed of second gear. This is a speed change process called inertiaphase.

In the case of 1-2 upshift, the revolutionary speed of the transmissiongear 41 (G12) will be reduced to N1, if the motor speed is changed toreach (N1−N2′), with the motor torque kept constant, as shown by thespeed change in the time chart of FIG. 12A. In this case:N2′=Ne/G42=G12×G21/G42×No  (Equation 3)

The G12 indicates the gear ratio of the transmission gear 41.

The (N1−N2) obtained from Equation 1 and Equation 2 was a negativevalue, but the (N1−N2′) obtained from Equation 1 and Equation 3 was0.181×No, a negative value. The direction of motor rotation was changedhalfway through the rotation so that the speed of the transmission gear41 (G12) was changed to N1.

In Step 8, the transmission control unit 8 determines if the speedchange has terminated or not. This determination is made by checking ifthe speed of the input shaft 36, i.e. the engine speed Ne has beensynchronized with the (N1×G12) or not.

In Step 9, the transmission control unit 8 operates the shift actuator63 so that the dog clutch 46 of the transmission gear 41 (G12) will beengaged. Since it is in the synchronized state, it can be easilyengaged, without giving any change to the operation of the transmission.

In Step 10, the transmission control unit 8 issues the motor torquereduction command. When the motor torque is reduced to “0” as shown bythe speed change in the time chart 2 of FIG. 12A, the engine torquetransferred to the transmission gear 55 (G42) through the motor 5 movesto the transmission gear 41 (G12), as shown in FIG. 12B.

In Step 11, the transmission control unit 8 determines that the torquechange 2 has terminated, since the motor torque has been reduced to “0”.

In Step 12, the transmission control unit 8 operates the shift actuator66 and releases the transmission gear 55 (G42), thereby terminating thegear shift. Since the motor torque is in the state of “0”, easy releasecan be achieved, without giving any change to the operation of thetransmission.

The description refers to the case of 1-2 upshift. The upshift up to 5thgear and downshift as well as jump-over gear shift can be performed inidentically the same manner.

FIG. 13 shows the motor control system. The motor 5 is a permanentmagnetic synchronous motor, for example. Three-phase alternating currentU, V and W are supplied by motor control equipment 7. Each arm of theinverter of the motor control equipment 7 is provided with a high speedswitching device 32 so that the d.c. voltage of a battery 6 is convertedinto 3-phase voltage of variable frequency. In response to the torqueinstruction and speed reference command from the transmission controlunit 8, the inverter control unit 33 controls the duty of the inverter,and feeds back the output of the current sensor 34 of each arm and theoutput of the angle detecting position sensor 35 of the rotor so thatthe torque and speed of the motor 5 will conform to the commands. Suchcontrol is a known art in the field of power electronics, and will notbe described.

FIG. 14 shows the relationship between motor torque and speed. What iscalled “4-quadrant control” is provided by the motor control equipment7.

The following description assumes that the direction of the motor torquefor assisting engine torque is positive.

In the case of so-called power-on upshift where upshift is carried outduring acceleration by the engine torque, if the motor torque isgenerated by torque phase, the operating point moves from point A topoint B. It is further moved to point C by inertia phase, and to point Dat the termination of the gear change.

In the case of the power-on downshift, the procedure is reversed.Starting from point D of FIG. 14, the operating point is moved to pointC by the torque phase, and to point B by the inertia phase. Gear shiftterminates at point A.

In the case of lift foot upshift and coast-down, the area is theso-called engine braking area where the engine absorbs driving force, sothe operating point moves to the first and second quadrants in FIG. 14.

The type of the motor is not restricted to the permanent magneticsynchronous motor so long as 4-quadrant control can be provided. It goeswithout saying that an induction motor or d.c. motor can be used.

FIG. 15 is a block diagram representing the transmission 2 as a secondembodiment of the present invention. What is different from FIG. 2 isthat the transmission gear 40 of the first intermediate shaft 39 is usedfor backing up. Instead, gear ratio of the transmission gear 59 secondintermediate shaft 53 is reduced to be used for sixth gear.

FIG. 16 shows an example of the operation mode of this transmission. Inthe present embodiment, the gear ratio is determined by a combination oftwo transmission gears. The engine torque is transferred from the inputshaft 36 to either the first intermediate shaft 39 or secondintermediate shaft 53, and is transferred from that intermediate shaftdirectly the output shaft 3. This mode is the drive mode, on the onehand. On the other hand, the assist mode is the mode where the enginetorque is transferred to the output shaft 3 after having beentransferred to another intermediate shaft through the motor. This is thesame as the case in FIG. 3. The 1st, 2nd, 3rd, 4th, 5th and 6th gearsare in the drive mode, while 0.5th, 1.5th, 2.5th, 3.5th, 4.5th and 5.5thgears are in the assist mode.

In either mode, engine torque is transmitted through two dog clutches.To perform power-on shift, connection of either one of the dog clutchesmust be changed, with the remaining one left unchanged, in order toprevent the torque from being suspended. Further, means must be providedto ensure that the transmission ratio in the assist mode will be themedian value of the transmission ratio in the drive mode. For 3.5th gearand thereafter, the gear ratio of each transmission gear is set bygiving consideration to these two restrictions.

FIG. 17 shows an example of the transmission ratio obtained from the setgear ratio and the combination thereof. It meets the aforementioned tworestrictions and corresponds to FIG. 16. The definition of each gearratio is shown in FIG. 17B. The transmission ratio in the assist mode isslightly smaller than the median value of the transmission ratio in thedrive mode. This is because the planned value is intentionallymisaligned, giving consideration to the motor inverter efficiency. Afterhaving aligned the following center distances, the misalignment was atmost 10% or so, although it was further increased from the plannedvalue.

FIG. 18 shows radiuses r1 through r18 of transmission gears forachieving these gear ratios and center distances L1 through L4determined thereby. The radius and center distances are defined in thedrawing attached to FIG. 17B. Since the transmission gear 40 has anidler, the center distance L1 can be determined by giving considerationonly to the transmission gear 41. Since center distance L4 is equal withrespect to the transmission gears 54 and 55, transmission gears 40 and41 and transmission gears 54 and 55 can be made to mesh each other fromboth sides of the input gears 37 and 38. Similarly, the center distanceL2 is equal with respect to the transmission gears 42 through 45, andthe center distance L3 is equal with respect to the transmission gears56 through 58; therefore, these gears can be made to mesh with eachother from both sides of the driven gears 49 through 52.

Further, the input shaft 36, first intermediate shaft 39, secondintermediate shaft 53 and output shaft 3 are not arranged on a flatplane, so there is no need of meeting L1=L2, and L3=L4. However, in thepresent embodiment, gear ratios G12 and G42 are equal to each other;thus, L1=L4.

The transmission shown in FIG. 15 permits a variety of gear combinationsin addition of the combination given in FIG. 17. FIG. 19 shows thecombinations other than those given above. A variety of intermediatetransmission ratios can be obtained. They are transmission ratios forthe engine, and this transmission also changes transmission ratio forthe motor. FIG. 20 shows all combinations including the transmissionratios for the motor. The portion enclosed by bold frames indicatestransmission ratio with respect to the motor. The other shows the gearratio with respect to the engine. The crosshatched section shows themode where the engine torque is transferred through the motor. The boldcharacters show the combinations of FIG. 17. Combinations of the G11 andG12, and G41 and G42 are also possible. Transmission ratio between theengine and motor is shown. This is possible when only one gear on theoutput shaft side is connected. When the combination shown by the boldframe is used, connection is prohibited. This is indicated by “−”. Thecombination marked with “×” refers to the case of double meshing, andrevolution is disabled in this state. As described above, thetransmission shown in FIG. 15 is capable of 48 transmissions ratios.

In the present embodiment, jump-over shift is also possible. It isapparent from FIG. 16 that 6-4 shift is performed through 4.5th gear,5-3 and 4-2 shift through 3.5th gear, and 3-1 shift through 2.5th or1.5th gear.

The 3-step jump-over shift is also performed in a similar manner. It isapparent from FIG. 16 that 6-3 shift is performed through 5.5th gear,and 5-2 and 4-1 shift through 3.5th gear.

Except for rapid step-on gas pedal, jump-over gear shift is a gear shiftwithout torque applied. The gear may be shifted directly to the desiredstep.

The present embodiment provides the advantage that the gear shift stepcan be expanded up to sixth gear and, at the same time, jump-over gearshift can be easily controlled without using the irregular secondarygear shift step.

The control flow and motor control are the same as those of the firstembodiment. The description in FIGS. 11 through 14 is directlyapplicable.

The present embodiment allows the engine and transmission to bedisconnected, without increasing the number of dog clutches. Thisincreases the efficiency of regenerative braking and provides asubstantial economical advantage. It also allows the transmission ratioof 1st through 5th gear to be designed in the same manner as before.Further, a large number of secondary transmission ratios can beobtained. Moreover, this is used to perform jump-over gear shift. Themotor speed can be changed independently of the engine. This increasesthe motor efficiency and provides a substantial economical advantage.

1. A transmission comprising: an input shaft connected to an engine; twoinput gear trains arranged on said input shaft; a first intermediateshaft; two first transmission gear trains having different rotationaldirections, connected with or disconnected from said first intermediateshaft with a first dog clutch, meshing with said input gear trains,respectively; a second intermediate shaft; two second transmission geartrains having gear ratios different from each other, connected with ordisconnected from said second intermediate shaft with a second dogclutch, meshing with said two input gear trains, respectively; a thirdtransmission gear train arranged on said first intermediate shaft andconnected with or disconnected from said first intermediate shaft; afourth transmission gear train arranged on said second intermediateshaft and connected with or disconnected from said second intermediateshaft; a driven gear train meshing with said third and fourthtransmission gear trains an output shaft commonly connected to saiddriven gear train; a differential gear box connected with said first andsecond intermediate shafts; and a motor operatively connected to saiddifferential gear box to apply torque relatively to said first andsecond intermediate shafts.
 2. A control unit of a transmissioncomprising: an input shaft connected to an engine; two input gear trainsarranged on said input shaft; a first intermediate shaft; two firsttransmission gear trains having different rotational directions,connected with or disconnected from said first intermediate shaft with afirst dog clutch, meshing with said two input gear trains, respectively;a second intermediate shaft; two second transmission gear trains havinggear ratios different from each other, connected with or disconnectedfrom said second intermediate shaft with a second dog clutch, meshingwith said two input gear trains, respectively; a third transmission geartrain arranged on said first intermediate shaft and connected with ordisconnected from said first intermediate shaft; a fourth transmissiongear train arranged on said second intermediate shaft and connected withor disconnected from said second intermediate shaft; a driven gear trainmeshing with said third and fourth transmission gear trains; an outputshaft commonly connected to said driven gear train; a differential gearbox connected with said first and second intermediate shafts; and amotor operatively connected to said differential gear box to applytorque relatively to said first and second intermediate shafts; whereinsaid control unit comprises steps of: engaging a first transmission gearof said two first transmission gear trains, engaging a firsttransmission gear of said third transmission gear train; engaging afirst transmission gear of said two second transmission gear trainsduring a drive operation; increasing torque of said motor therebyshifting transmitting torque of the first transmission gear of said twofirst transmission gear trains to the first transmission gear of saidtwo second transmission gear trains; disengaging said first transmissiongear of said first two transmission gear trains when the transmittingtorque thereof has been reduced close to zero; gradually approaching arevolution speed of the first intermediate shaft to a secondtransmission gear of said two first transmission gear trains, whileoutput shaft torque is maintained by said motor; connecting the secondtransmission gear of said two first transmission gear trains, when therevolution speed of said first intermediate shaft has synchronized withthat of the second transmission gear of said two first transmission geartrain trains; reducing the torque generated from said motor to zero,thereby disconnecting the first transmission gear of the secondtransmission gear train, and providing at least one gear step of drivemodes between gear steps before and after a gear shift operation.
 3. Acontrol unit of a transmission comprising: an input shaft connected toan engine; two input gear trains arranged on said input shaft; a firstintermediate shaft; two first transmission gear trains having differentrotational directions, connected with or disconnected from said firstintermediate shaft with a first dog clutch, meshing with said two inputgear trains; a second intermediate shaft; two second transmission geartrains having gear ratios different from each other, connected with ordisconnected from said second intermediate shaft with a second dogclutch, meshing with said two input gear trains, respectively; a thirdtransmission gear train arranged on said first intermediate shaft andconnected with or disconnected from said first intermediate shaft; afourth transmission gear train arranged on said second intermediateshaft and connected with or disconnected from said second intermediateshaft; a driven gear train meshing with said third and fourthtransmission gear trains an output shaft commonly connected to saiddriven gear train; a differential gear box connected with said first andsecond intermediate shafts; and a motor operatively connected to saiddifferential gear box to apply torque relatively to said first andsecond intermediate shafts; wherein said control unit comprises stepsof: engaging a first transmission gear of said first transmission geartrains, engaging a first transmission gear of said third transmissiongear train; engaging a first transmission gear of said fourthtransmission gear train during a drive operation; increasing the torqueof said motor; thereby shifting transmitting torque of the firsttransmission gear of said third transmission gear train to the firsttransmission gear of said fourth transmission gear train; disengagingsaid first transmission gear of said third transmission gear train whenthe transmitting torque thereof has been reduced close to zero;gradually approaching a revolution speed of the first intermediate shaftto a second transmission gear of said third transmission gear train,while output shaft torque is maintained by said motor; connecting thesecond transmission gear of the third transmission gear train, when therevolution speed of said first intermediate shaft has synchronized withthat of the second transmission gear of the third transmission geartrain; and reducing the torque generated from said motor to zero,thereby disconnecting the first transmission gear of thefourth-transmission gear train.
 4. An automobile comprising: an engine;an electrical controlled throttle valve arranged on said engine; anengine control apparatus for controlling said throttle valve; atransmission further comprising: an input shaft connected to saidengine, two input gear trains arranged on said input shaft, a firstintermediate shaft, two first transmission gear trains having differentrotational directions, connected with or disconnected from said firstintermediate shaft with a first dog clutch, meshing with said two inputgear trains, respectively; a second intermediate shaft; two secondtransmission gear trains having gear ratios different from each other,connected with or disconnected from said second intermediate shaft witha second dog clutch, meshing with said two input gear trains,respectively; a third transmission gear train arranged on said firstintermediate shaft and connected with or disconnected from said firstintermediate shaft; a fourth transmission gear train arranged on saidsecond intermediate shaft and connected with or disconnected from saidsecond intermediate shaft; a driven gear train meshing with said thirdand fourth transmission gear trains; an output shaft commonly connectedto said driven gear train; a differential gear box connected with saidfirst and second intermediate shafts; and a motor operatively connectedto said differential gear box to apply torque relatively to said firstand second intermediate shafts; and a motor control unit for controllingtorque and revolution speed of said motor so as to shift engine outputto the next position gear whereby the speed is changed, wherein at leastone gear step of drive modes between gear steps before and after a gearshift operation is provided.
 5. The transmission according to claim 1,wherein an assist mode transmission ratio is less than a median value ofa drive mode transmission ratio.
 6. The transmission control unitaccording to claim 4, wherein an assist mode transmission ratio is lessthat a median value of a drive mode transmission ratio.